Our results indicate that parenthood was associated with a number of negative outcomes, particularly for mothers. Young adult mothers had poorer dietary intake and higher BMI compared with women without children, and both mothers and fathers had lower amounts of physical activity compared with young adult nonparents, despite adjustment for potential confounding variables (including SES). Young adult fathers had similar BMIs and dietary intake compared with nonfathers.
Our finding that mothers differed significantly from women without children in intake of total energy, percent saturated fat, vegetables, and sugar-sweetened beverages but not in fruit, dairy, whole grains, calcium, or fiber intake may suggest that mothers have conflicting factors that influence their dietary intake outcomes. These factors may include wanting to be good role models of healthy dietary intake (eg, eating fruits, dairy) but, at the same time, having less available time to eat healthy. For example, mothers may find it easier and less time-consuming to cook more palatable, yet high-fat, food for children (eg, macaroni and cheese, chicken nuggets) and to eat more snack foods with children. Another potential explanation for the higher energy intake and BMI for mothers is that they may modify their milk consumption habits, including drinking the higher fat milk that their children drink (eg, whole milk).
The finding of decreased physical activity for parents is consistent with previous research reporting cross-sectional and longitudinal associations between parenthood and decreased physical activity.4,7
Possible explanations for lower physical activity levels among parents versus nonparents is that parents may have difficulty finding time to engage in physical activity. Many parents find caring for young children to be physically and emotionally demanding, and therefore may either not be able to find the time to exercise or, if they have time, they are often too tired to do so. Another possible explanation for the differences in physical activity observed between parents and nonparents is that the measures of physical activity in our study may not adequately capture the types of activities in which parents engage. Rather than purposefully exercising during their leisure time, parents of young children may have many short bursts of physical activity when chasing or playing with their child, carrying their child, walking to the park with their child, or wrestling with their child.
Our findings suggest that mothers of young children are at increased risk for higher BMIs but fathers are not. Weight differences in parents versus nonparents have not previously been identified in research, and fathers have not been analyzed separately. This finding regarding BMIs may be related to primary caregiver status. Typically, mothers take the role of primary caregiver in the home, regardless of whether they work outside the home (part- or full-time) or are stay-at-home mothers. Taking primary responsibility to feed, nurture, and provide overall care for the children may put mothers at increased risk for weight gain and poorer dietary intake because they have less time for physical activity, eat more of the palatable foods children prefer (eg, high in saturated fat and calories), and have more interrupted sleep patterns (eg, responsible for night feedings or wakeups). Mothers in our study may also have postpartum weight retention because the majority of parents had children 1 year old or younger. The nonsignificant BMI findings for fathers may be related to the fact that fathers in this study are young and are early in their establishment of dietary and physical activity patterns. Therefore, the weight implications of being less physically active may not yet have come to fruition (eg, chronic disease risk).
Strengths and Limitations
This study has a number of strengths, one of which is the use of a large, diverse, population-based sample. The size, gender, race and ethnicity, and socioeconomic diversity of the study sample allows for generalizability of these study findings to other populations of young adults from US metropolitan areas. This research builds on previous studies that primarily used participant samples from clinical settings or university classrooms. In addition, this study included data from both mothers and fathers. The majority of the research on parenthood has focused on mother self-report. Furthermore, this sample is part of a longitudinal cohort study. Thus, analyses were adjusted for outcomes at time 2, which accounted for behavior and weight differences that may have existed before the parents had their children, therefore allowing for a better understanding of the temporal relationship between having children and individuals' weight and dietary and physical activity behaviors.
Our findings must also be interpreted in light of certain limitations. One limitation is that participants were not asked about barriers to healthy eating and exercise that they experience as a parent. Thus, little information is available to help understand these barriers. Another limitation is that these results are not generalizable to parents with older children. Future research is needed to understand how parents' diet and activity habits are associated with having older children and how parents' health habits may change as their children grow older.
Implications for Health Care Professionals
Results of our study have implications for pediatricians and other health care providers who have regular contact with parents of young children. Providers may find benefit in talking with new parents about their personal barriers to eating healthy and being physically active, and work with them to identify ways to overcome these barriers and incorporate physical activity and healthy eating into their new lifestyle. New parents may be particularly receptive to ideas to increase their physical activity and healthful dietary intake that allow them to model healthful behavior for their children, such as attending parent/child exercise classes or going for walks together. Future research is needed to explore the effectiveness of these types of discussions between health care providers and new parents.